By pulling out a bomb so that it explodes while Darkhammer is vulnerable after throwing the Ball & Chain, one can kill Darkhammer with 1 jump attack + quickspin after the bomb explodes. The position of the bomb is not important.
Darkhammer will die if its tail is hit by Mortal Draw once. Stand to the right of the tail and far enough away that Mortal Draw will not miss or clank on the armor.
Note that there are multiple ways to make Darkhammer throw the Ball & Chain, such as rolling around it and waiting, waiting and then rolling up to it, and clawshotting the ceiling past it.
After Darkhammer throws the Ball & Chain, hit its tail 5 times with jump attack(s) and quickspin(s).
After Darkhammer throws the Ball & Chain, shoot its tail twice with bomb arrows.
There's 1 frame between defeating Darkhammer and the cutscene beginning on which the player can press A to pick up the Ball & Chain and immediately get it after the cutscene ends.